The proposed research entails anatomical, biochemical, and ablation- behavior analyses of neocortex in neurologically primitive mammals. The long term objective is to discover the contribution of sensory, association, and motor cortex to the neurological and psychological adjustment of man and animals to their environment. The specific aims include the assessment of the structure and function of major areas of neocortex in a number of neurologically generalized mammals (including opossums, armadillos, rabbits, rats, hedgehogs, tree shrews, lemurs, and bushbabies) specifically selected for their sequential common ancestry with Primates, in order to allow inferences to the neurological and psychological condition of the extinct animals in the Primate ancestral lineage. The methods include anatomical tract-tracing techniques to determine the changes in the location, extent, and connections of sensory and motor areas, receptor-binding and immunohistochemical techniques to determine changes in the biochemical characteristics of that same areas, and ablation-behavior techniques to determine the changes in the behavioral contributions of the areas. In this manner the evolutionary development of Primate neocortex is traced from its most primitive mammalian form to its current form in an attempt to understand the contributions of its many parts.